An awesome place to stay is the Green Tortoise hostel. Relatively cheap with free dinner 3 nights a week, and more often than not free beer keg all night. A lot of skaters staying there, a lot of sluts too. And it's in the very center of a lot of skate spots. SF is an amazing city to just cruise around all day and night and see what you can find, I found that better than just going to the usual spots, maybe save those for one day just to satisfy your curiosity. China banks is worth a visit just to realize how gnarly it is to skate. If you do end up staying at the hostel, check it out it's right down the street, so is pier 7, which can still be skated as a manny pad last time I went. If you are looking for ledges, the city is full of a lot of random ones that are usually down a huge hill. A stop to the DLX store on market street would be ideal, those dudes are cool and super helpful to visiting skateboarders. Have a fun trip dude, that city is amazing.